Tuesday, August 23, 2005

Pyoderma in the Canine: "Pyoderma
Bacterial skin disease
Pyodermas are common in small animal practice, particularly in the dog.
There are several ways of classifying pyoderma but the easiest way to understand this disease is to think about the thickness of the skin and to define the infection on how deep the bacteria infect the skin cell layers
Surface pyoderma: This is where bacteria colonise the outermost layer of the skin.
Superficial pyoderma: The bacterial infection is at the level of the intact hair follicle.
Deep pyoderma: The bacterial infection extends beneath and beyond the hair follicle.
Causative bacteria
The vast majority of cases involve a natural resident of the skin called Staphylococcus Intermedius which becomes pathogenic (disease causing) when the skin environment changes for a number of different reasons. Other bacteria and other micro-organisms may be involved but some reports suggest that over 90% of cases have Staphylococcal involvement.
What does pyoderma look like?
The most common, owner response is that the dog itches, has red areas, often with pimples or scabs and the pet may smell. Surface pyodermas may show as areas of redness and irritation, often developing in raised round, scabs. Superficial pyodermas produce yellow spots which then break out into larger wheals and scabs. Deep pyoderma can make pets systemically ill and produce abscesses and oozing, inflamed channels in the skin surface. Certain areas may be particularly prone to infection. Interdigital areas, inside ears, the groin and along the middle of the back are common sites in the dog. Other diseases such as yeast infections can look very similar and so if there isn't a rapid resolution with home treatment, seek professional advice. "
Why does pyoderma occur?

There are too many reasons to list here but a few of the common reasons are suggested below.

Primary pyoderma

There is little doubt that occasionally pyoderma may develop spontaneously and for no obvious clinical reason (idiopathic). The general consensus is that these dogs probably have a compromised immune system or a congenital / inherited factor affecting skin immune systems.

Atopy

A name given to contact and inhaled, chronic hypersensitivity disorders, often with an inherited base. Certain breeds are particularly susceptible. Speak to your veterinarian at length on this complex and difficult subject. Allergens incriminated vary from the house dust mite and plant pollens to human skin cells! The inflammatory skin changes, again, leave your pet open to secondary pyoderma.

Ectoparasites

Especially fleas. Apart from the trauma and irritation of individual flea bites, many dogs develop an allergy to flea saliva causing a generalized skin inflammation. This changing skin environment allows pyoderma to develop. See Flea Control and Parasitic Skin Disease In any case of pyoderma, assume fleas may have a role to play until proven otherwise.

Dietary allergy

Not as common as people would like to believe but is occasionally seen in dogs and because of the common daily inclusion of beef, chicken and wheat based products in dog foods we are seeing dietary intolerances being manifested as skin allergies with secondary pyoderma. Change to a hypoallergenic diet, such as Hills Canine d/d after consultation with your veterinarian.